Only swap undefined for the global object if necessary in the prologue

src/x87/lithium-codegen-x87.cc

Index: src/x87/lithium-codegen-x87.cc
diff --git a/src/x87/lithium-codegen-x87.cc b/src/x87/lithium-codegen-x87.cc
index af118d5edfed23dbd0765b800e567bf5ce56347a..ba650abbbb6c2a386ff1a94de4ada55488dd476d 100644
--- a/src/x87/lithium-codegen-x87.cc
+++ b/src/x87/lithium-codegen-x87.cc
@@ -110,7 +110,7 @@ bool LCodeGen::GeneratePrologue() {
     // Sloppy mode functions and builtins need to replace the receiver with the
     // global proxy when called as functions (without an explicit receiver
     // object).
-    if (graph()->this_has_uses() && is_sloppy(info_->language_mode()) &&
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
         !info_->is_native()) {
       Label ok;
       // +1 for return address.